In general, a retro-reflection product is a reflector for returning and reflecting an incident light, which is a reaching light, to a light source when a light emitted from an object (the light source) reaches another object. The retro-reflection product facilitates indication even in a dark place around it by processing a surface of a sheet body by a desired shape or pattern and attaching the processed body to a sign board or clothing by an adhesive or sewing. Therefore, the retro-reflection product enables people around it to surely confirm a position, thereby providing a great effect in worker protection and safety if being attached to clothing for workers working on a road or in a dangerous place such as a street cleaner, a fireman, a policeman, a factory worker, a construction worker, and a safety officer.
The retro-reflection product has been disclosed in Korean Patent No. 10-0349990 entitled “METHOD FOR FABRICATING MULTI COLOR RETRO-REFLECTOR FOR TRANSCRIPT” and Korean Utility Model Registration No. 20-0381037 entitled “RETRO-REFLECTION ARTICLE HAVING WHOLE-SURFACE TRANSPARENT PROTECTION FILM”. A method for fabricating the retro-reflection product has been in detail disclosed in Korean Patent Laid-Open No. 2000-0024397 published on May 6, 2000 and entitled “METHOD FOR FABRICATING PATTERN RETRO-REFLECTION PRODUCT WITH DOUBLE EFFECT”.
However, when a glass bead layer attached to a PET film or a PE film is processed by primary and secondary coating, the conventional retro-reflection product uses solvent based urethane resin containing a low boiling point solvent such as Methyl Ethyl Ketone (MEK) and Ethyl Acetate (EA) and a high boiling point solvent such as cyclohexanone and DiMethylFormamide (DMF), that is, solvent based polyurethane resin containing polyol, low molecular weight diol, low molecular weight diamine, and isocyanate. In the case of using the solvent based urethane resin, the conventional retro-reflection product not only generates harmful materials to a human body because of toxicity of itself and increases a fire dangerousness but also involves a great dangerousness against workers' health.
In detail, the solvent not only exerts a bad influence upon worker's health and safety and causes lethal environmental pollution but also produces a cancer and causes nausea and skin trouble because of its contained cancer-causing materials and exerts a bad influence upon a human body for long-time use.
In particular, the retro-reflection product processed by the primary and secondary coating using the solvent based polyurethane resin remarkably deteriorates an adhesive strength with the aluminum layer and an adhesive power with the glass bead layer because it is in a state where polyurethane polymer chains are dissolved (unchained) in solvent.